Future wireless communication systems will be a system with high transmission rate and high reliability. Meanwhile, receiver complexity must be within an acceptable range. ITU's IEEE802.16 Serial Standard is a standard series which especially address wireless access problems. IEEE802.16 has attracted wide attention and been closely studied worldwide.
In the IEEE802.16e proposal, multi-antenna systems for an OFDMA will be improved in terms of transmission rate and receiver complexity. Taking a coding matrix C of IEEE802.16e, which has the highest transmission rate as an example, the coding matrix can be represented by Equation 1:
                              c          =                                    1                                                1                  +                                      r                    2                                                                        ⁢                          (                                                                                                                  s                        i                                            +                                              jr                        ·                                                  s                                                      i                            +                            3                                                                                                                                                                                                  r                        ·                                                  s                                                      i                            +                            1                                                                                              +                                              s                                                  i                          +                          2                                                                                                                                                                                                        s                                                  i                          +                          1                                                                    -                                              r                        ·                                                  s                                                      i                            +                            2                                                                                                                                                                                                  jr                        ·                                                  s                          i                                                                    +                                              s                                                  i                          +                          3                                                                                                                                )                                      ,                                  ⁢                  r          =                                                    -                1                            +                              5                                      2                                              [                  Eqn          .                                          ⁢          1                ]            
For this solution, at a Timing i, Transmitting antenna 1 and Transmitting antenna 2 respectively transmit [si+jr·si+3, si+1−r·si+2]. At Timing i+1, Transmitting antenna 1 and Transmitting antenna 2 respectively send [r·si+1+si+2, jr·si+si+3], where j=sqrt(−1), si is a modulated symbol sent at Timing i.
However the conventional solution has the following problems:
Firstly, in IEEE802.16e, according to OFDMA spatial-temporal encoding scheme, a coding transmission rate R of the coding solution is equal to ‘2’, which is relatively low. Secondly, in IEEE802.16e, when the above solution is adopted, a maximum likelihood sequential decoding algorithm complexity of the receiver reaches M4. For high dimensional modulation levels, the decoding method suffers from poor practicality. The high operational complexity means a too high requirement for the devices.